His date of birth is uncertain but he was a grown man when he fought at the Battle of Knockdoe in 1504, and had already been a widower for several years.
He married Anne (or Anny), daughter and heiress of Philip de Birmingham and Ellen Strangeways, who was, in turn, the daughter of Nicholas Strangeways, Chief Remembrancer of the Exchequer of Ireland and his wife Alice Delahyde; they had one surviving son, Robert Plunkett, 5th Baron of Dunsany.
Dunsany, who was described as "a valiant man", and who had already seen military action at the Battle of Knockdoe, where he had fought under the command of Kildare's father, raised troops to help crush the rebellion.
In pursuit of the O'Connors on 24 January 1521, his horse broke a leg and he was killed on the spot by his enemies.
[1]: 25 Their tombstone is plain with large Latin lettering, and reads in translation "Here lie the bodies of Sir Edward Plunkett, Knight, Lord of Dunsany, who was slain at Killaderry in Offaly in AD 1521, and of An(n)y Bermingham his wife, AD 1500".